Re: [omc-boats] Suggestion for Ball Drive Parts on 1969 or 1970 120

On Mon, 15 May 2006, A Mark wrote:
> The ball gear has a couple of the teeth shaved off
> (pointed) from what looks to be someone 'trimming' the
> lower unit. Since the boat has not been in the water
> for at least 5 years, I want to replace the ball
> drive,

Does your drive use the ball gear that is retained by a nut or the one that
is pressed onto the shaft? The latter is much harder to find - that's what
was on my 1970 boat. I've been variously told that the Sierra kits have
the nut-gears that only fit 71/72 or newer. I watched ebay for a couple
months (and emailed everyone I found who was selling older OMC parts)
before finding a press-fit gear. If you want, email me and I can send you
a few likely contacts to try.

Disassembly is fairly simple - you have to remove the outdrive, take off
the retainer plates on each side (three bolts on the intermediate housing,
four on the outdrive), and then pull the shafts. If you're just replacing
the ball gear and not the entire shaft, you'll need a fairly large press
and/or a bearing puller to get them apart.

You might as well replace the rear intermediate housing bearing as this
time as well - mine was destroyed and I think they are inadequately
lubricated (since there's no easy way to check intermediate housing oil
level). A new bearing (206K C3) should be available from a local
industrial supply shop. I bought replacement shims (no gaskets used) from
Paradise Marine in WA. Some of the o-rings are somewhat hard to find, but
I found close matches (#140 was one) at a local place - if I did it again
I'd probably spend the few dollars and buy them from Paradise again.

I ended up spending $60 for the intermediate side ball gear (and shaft),
$55 for the outdrive ball gear (reused the old shaft - important for
maintaining tolerances without reshimming), $25 for shims, $15 for a
bearing, and another $10 for various o-rings and snap-rings. It took me a
few afternoons to do all the work (I also replaced the water pump and some
seals), but you'll probably be quicker.

Best wishes,

Ethan

-- 
<A HREF="http://www.engr.wisc.edu/~brodskye/"> Ethan Brodsky </A>
UW FutureCar Team Paradigm: Two-Year FutureCar Challenge Winner
UW-Madison Clean Snowmobile Team: Winner of the 2004 SAE CSC
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